Alu M52 Overheating --- Update: Sill having issues

[Chilezen]

Over a month later and I have an update.

I have replaced the factory water pump with a Stewart pump. I do like the design of the Stewart, the way it directs the water up. Pretty smart.

Upon inspecting the factory pump, I found..... nothing of interest. It looked fine. No rubbing or scars on the impellers. Spun freely, quietly.



It had a little bit of "grit" stuck in with the lube around the O-ring, which I thought was odd, but I've already been seeing debris come out in the coolant, so it's no surprise to see it there.

So, yay, I guess. It was another good part I didn't need to replace.


I've also installed an engine-block-drain-hose, the idea of which I got from Charlie. Sh3rpak!ng



Around the hose, bolted to the block, is an aluminum heat shield I designed. It holds the hose in place, away from the exhaust. I should have gotten a better picture of it by itself. Hopefully you get the idea.
But anyway so far it's holding up, no leaks that I've seen yet.


Back to the problem.

I found that the intake elbow had a crack in it. Could have caused a vacuum leak. Very possible that this could be causing the hot running engine!

I replaced the intake boot and water pump together. I bled the coolant the "normal" way, by propping the front up on jackstands. Did a decent job I suppose.

Drove the car.

Problem is still here.

Temp gets hot in the beginning (maxxed out at 107°C) and then fell down around the thermostat rating (around 80°). It would climb when I drove the car hard/under load, as usual.
However, I have noticed the temp swings are less severe, and it didn't get as hot.

The coolant does still leak from the reservoir cap, and from underneath the rear of the head, as usual.

The heater will blow hot air normally, except when the temp climbs/under load. Even when the engine says it has warmed up (showing 90°+) after a cold start, the heater blows cold. But it will blow hot air after the temp has spiked and come back down.

So there's nothing left for me to do. Every component is new (if not twice new).

It has to be the engine/head.

And it has an appointment with the engine builder at the end of this month.

I did everything I could.

[reelizmpro]

Did you not rent a block tester from a parts store like I told you to? It's a very simple test that takes minutes. Had I done it sooner it would have saved me so much time and trouble because like you, I too unnecessarily changed the water pump, radiator, hoses, reservoir cap, etc. All the symptoms you mentioned, I had experienced with my S52 swap...that's why I bought that cylinder head from you just incase. Luckily, it was just a bad headgasket and my head was good.

[Chilezen]

Did you not rent a block tester from a parts store like I told you to?

I have done everything I could except that, for two reasons:

I did a leak-down test and concluded that the head gasket seems to be fine, because I didn't detect leakage into the coolant. It's not a 100% confirmation, but it wasn't as obvious as the problem makes itself.
Somebody (mjweimer) did suggest to perform that test, and somebody else (moatilliatta) commented the test is a hit-or-miss when you have a leak. That makes sense, and I have a leak, so I haven't. But I can anyway.

[e30davie]

"The coolant does still leak from the reservoir cap, and from underneath the rear of the head, as usual."

why you no fix this. its supposed to be sealed pressurised system.

[bimr84]

You can use the e39 m52 thermostat housing which has a bleeder screw built into it. Makes bleeding a 24v much easier.

11531740478

[Chilezen]

"The coolant does still leak from the reservoir cap, and from underneath the rear of the head, as usual."

why you no fix this. its supposed to be sealed pressurised system.

Yes, I'm aware of this. I don't know why it leaks. I don't know how to fix it. I replaced both items, brand new. The new ones leak just like the other ones. There shouldn't be any secret to putting a cap on the reservoir and sealing the system. I feel like an idiot for missing something simple. If there's something that could help, I'd love to know!


--I haven't said this before but maybe this means something: I'll drive the car, stop, and I hear hissing from the cap. But I don't feel any fluid spraying out. When I slowly open the cap, I hear a new hissing, the exact sound of pressure being released from the system. So, there is pressure, and I can open the cap and the pressure releases. This is clear as day. But, I still see water marks inside the engine bay, coming from this area. Pictures from page 1:

The new reservoir looks like the old one: covered in coolant.

I don't know how fluid is getting out. I've tried a "normal" amount of tightening. A very tight cap. A loose cap. All same story. With two res's and caps.

You can use the e39 m52 thermostat housing which has a bleeder screw built into it. Makes bleeding a 24v much easier.

11531740478

I've seen this used. I will say I have vacuum bled the system, which was recommended by the shop I'm taking the car to. He always has success with it. I felt successful too when I did it. But yes, maybe that housing could help as well.

[reelizmpro]

My coolant cap didn't just leak, it expelled coolant like it was designed to do when the system is over pressurized. The cap is doing it's job by trying to maintain system pressure. This is why I say, you need to test for exhaust gasses in the coolant. If the test fluid turns from Blue to Yellow at all you know you have a problem.

[mjweimer]

My coolant cap didn't just leak, it expelled coolant like it was designed to do when the system is over pressurized. The cap is doing it's job by trying to maintain system pressure. This is why I say, you need to test for exhaust gasses in the coolant. If the test fluid turns from Blue to Yellow at all you know you have a problem.

+1

Given you have thoroughly checked all other components, I think performing this test would be worthwhile and the next logical step. I don't think it would be $$$ wasted at this point and will help set direction for the next steps.

[reelizmpro]

Exhaust gas in the cooling system is also the reason why you can't bleed the system.

[Chilezen]

My coolant cap didn't just leak, it expelled coolant like it was designed to do when the system is over pressurized. The cap is doing it's job by trying to maintain system pressure.

Given you have thoroughly checked all other components, I think performing this test would be worthwhile and the next logical step. I don't think it would be $$$ wasted at this point and will help set direction for the next steps.

Understood, I agree with your reasoning. Except for how, the cap should be draining it through the drain tube, which it does, but only the drain tube, and not past the threads of the cap as well. Anyway, yes, I'll rent a tester from the auto store.
Exhaust gases would probably explain the weird phenomenon of a hot/cold heater.

[mjweimer]

Understood, I agree with your reasoning. Except for how, the cap should be draining it through the drain tube, which it does, but only the drain tube, and not past the threads of the cap as well. Anyway, yes, I'll rent a tester from the auto store.
Exhaust gases would probably explain the weird phenomenon of a hot/cold heater.

I really hope you can get to the bottom of the issue...I imagine it has been frustrating. Let us know what you find out with the combustion gas testing.

[reelizmpro]

Understood, I agree with your reasoning. Except for how, the cap should be draining it through the drain tube, which it does, but only the drain tube, and not past the threads of the cap as well. Anyway, yes, I'll rent a tester from the auto store.
Exhaust gases would probably explain the weird phenomenon of a hot/cold heater.

It's not leaking past the threads. It's releasing through the cap itself. Look at the design of the cap, it's a pressure regulating cap which means it actually opens itself to relieve pressure and protect the cooling system. I've experienced this with my swap car.

[2mAn]

At this point I think it’s what you’ve feared all along and we’re hoping it wasn’t... but it’s related to the long block itself. Fingers crossed it’s a head gasket and that’s it. The leaking in the back makes me think that, did they deliver it to you as an assembled long block? Hopefully they will take some ownership of this when the problem is discovered

[Chilezen]

I received the engine as a long block, yes. Almost no accessories attached.

Within this past week, I didn't have time for that simple test for combustion gases.

I did drive the car 2 hours up to the shop on Saturday, so it's out of my hands/head. I had to add half a gallon of water 3 times. otherwise the drive was fine, I kept the temp under check. Compared to before, the new pump seems to have helped dampen the issue, so that's nice.

We'll see what happens! I also asked them to fix the inoperable Vanos. The shop was busy so it's not looking like a quick fix. I mentioned my intention to drive up to the E30 Picnic at the end of June, and he said that's enough time to resolve the problem. Yeah, fingers crossed!

[2mAn]

I mentioned my intention to drive up to the E30 Picnic at the end of June, and he said that's enough time to resolve the problem. Yeah, fingers crossed!

End of June?... I wonder how close I will be to completing my Twin Spark build by then haha